Vulkan: Fix FS array output location assignment

src/libANGLE/renderer/vulkan/GlslangWrapper.cpp

@@ -508,6 +508,13 @@ void AssignAttributeLocations(const gl::ProgramState &programState,
     }
 }
 
+std::string RemoveArrayZeroSubscript(const std::string &expression)
+{
+    ASSERT(expression.size() > 3);
+    ASSERT(expression.substr(expression.size() - 3) == "[0]");
+    return expression.substr(0, expression.size() - 3);
+}
+
 void AssignOutputLocations(const gl::ProgramState &programState,
                            IntermediateShaderSource *fragmentSource)
 {
@@ -526,12 +533,27 @@ void AssignOutputLocations(const gl::ProgramState &programState,
         {
             const sh::OutputVariable &outputVar = outputVariables[outputLocation.index];
 
+            // In the following:
+            //
+            //     out vec4 fragOutput[N];
+            //
+            // The varying name is |fragOutput[0]|.  We need to remove the extra |[0]|.
+            std::string name = outputVar.name;
+            if (outputVar.isArray())
+            {
+                name = RemoveArrayZeroSubscript(name);
+                if (outputVar.isArrayOfArrays())
+                {
+                    name = RemoveArrayZeroSubscript(name);
+                }
+            }
+
             std::string locationString;
             if (outputVar.location != -1)
             {
                 locationString = "location = " + Str(outputVar.location);
             }
-            else if (std::find(implicitOutputs.begin(), implicitOutputs.end(), outputVar.name) ==
+            else if (std::find(implicitOutputs.begin(), implicitOutputs.end(), name) ==
                      implicitOutputs.end())
             {
                 // If there is only one output, it is allowed not to have a location qualifier, in
@@ -541,7 +563,7 @@ void AssignOutputLocations(const gl::ProgramState &programState,
                 locationString = "location = 0";
             }
 
-            fragmentSource->insertLayoutSpecifier(outputVar.name, locationString);
+            fragmentSource->insertLayoutSpecifier(name, locationString);
         }
     }
 }

src/tests/gl_tests/GLSLTest.cpp

@@ -488,6 +488,19 @@ class GLSLTest : public ANGLETest
         glDeleteProgram(program);
         ASSERT_GL_NO_ERROR();
     }
+
+    void verifyAttachment2DColor(unsigned int index,
+                                 GLuint textureName,
+                                 GLenum target,
+                                 GLint level,
+                                 GLColor color)
+    {
+        glReadBuffer(GL_COLOR_ATTACHMENT0 + index);
+        ASSERT_GL_NO_ERROR();
+
+        EXPECT_PIXEL_COLOR_EQ(getWindowWidth() / 2, getWindowHeight() / 2, color)
+            << "index " << index;
+    }
 };
 
 class GLSLTestNoValidation : public GLSLTest
@@ -535,6 +548,74 @@ void main()
     ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Simple(), kFS);
 }
 
+// Test that array of fragment shader outputs is processed properly and draws
+// E.g. was issue with "out vec4 frag_color[4];"
+TEST_P(GLSLTest_ES3, FragmentShaderOutputArray)
+{
+    GLuint fbo;
+    glGenFramebuffers(1, &fbo);
+    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, fbo);
+
+    GLuint textures[4];
+    glGenTextures(4, textures);
+
+    for (size_t texIndex = 0; texIndex < ArraySize(textures); texIndex++)
+    {
+        glBindTexture(GL_TEXTURE_2D, textures[texIndex]);
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, getWindowWidth(), getWindowHeight(), 0, GL_RGBA,
+                     GL_UNSIGNED_BYTE, nullptr);
+    }
+
+    GLint maxDrawBuffers;
+    glGetIntegerv(GL_MAX_DRAW_BUFFERS, &maxDrawBuffers);
+    ASSERT_GE(maxDrawBuffers, 4);
+
+    GLuint readFramebuffer;
+    glGenFramebuffers(1, &readFramebuffer);
+    glBindFramebuffer(GL_READ_FRAMEBUFFER, readFramebuffer);
+
+    constexpr char kFS[] = R"(#version 300 es
+precision highp float;
+
+out vec4 frag_color[4];
+
+void main()
+{
+    frag_color[0] = vec4(1.0, 0.0, 0.0, 1.0);
+    frag_color[1] = vec4(0.0, 1.0, 0.0, 1.0);
+    frag_color[2] = vec4(0.0, 0.0, 1.0, 1.0);
+    frag_color[3] = vec4(1.0, 1.0, 1.0, 1.0);
+}
+)";
+
+    ANGLE_GL_PROGRAM(program, essl3_shaders::vs::Simple(), kFS);
+
+    GLenum allBufs[4] = {GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2,
+                         GL_COLOR_ATTACHMENT3};
+
+    constexpr GLuint kMaxBuffers = 4;
+
+    // Enable all draw buffers.
+    for (GLuint texIndex = 0; texIndex < kMaxBuffers; texIndex++)
+    {
+        glBindTexture(GL_TEXTURE_2D, textures[texIndex]);
+        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + texIndex, GL_TEXTURE_2D,
+                               textures[texIndex], 0);
+        glFramebufferTexture2D(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + texIndex, GL_TEXTURE_2D,
+                               textures[texIndex], 0);
+    }
+    glDrawBuffers(kMaxBuffers, allBufs);
+
+    // Draw with simple program.
+    drawQuad(program, essl3_shaders::PositionAttrib(), 0.5f, 1.0f, true);
+    ASSERT_GL_NO_ERROR();
+
+    verifyAttachment2DColor(0, textures[0], GL_TEXTURE_2D, 0, GLColor::red);
+    verifyAttachment2DColor(1, textures[1], GL_TEXTURE_2D, 0, GLColor::green);
+    verifyAttachment2DColor(2, textures[2], GL_TEXTURE_2D, 0, GLColor::blue);
+    verifyAttachment2DColor(3, textures[3], GL_TEXTURE_2D, 0, GLColor::white);
+}
+
 TEST_P(GLSLTest, ScopedStructsOrderBug)
 {
     // TODO(geofflang): Find out why this doesn't compile on Apple OpenGL drivers